1. Field
The present disclosure relates generally to manufacturing composite structures and, in particular, to manufacturing airfoils using composite materials. Still more particularly, the present disclosure relates to a method and apparatus for manufacturing composite wind turbines or aircraft airfoils.
2. Background
A wind farm is a type of power plant that produces electrical power from the wind. A wind farm may have from a few dozen to several hundred wind turbines. Wind turbines in a wind farm may cover hundreds of square miles.
A wind turbine is a rotary device configured to generate energy using the wind. A wind turbine generates mechanical energy in response to the movement of wind. This mechanical energy may be turned into electricity. A wind turbine comprises blades that are rotatably mounted to a structure. An electrical generator may be used to generate electricity from movement of the blades.
Wind turbines used in wind farms typically have three blades and are pointed into the wind through computer controlled motors. These wind turbine blade tips may have speeds over about 200 miles per hour. The blades in a wind turbine may rotate at about 10 to about 22 revolutions per minute.
The blades in a wind turbine are airfoils with shapes that are similar to those for aircraft wings. Traditionally, a blade for a wind turbine has two curved surfaces or shells. These surfaces are joined at a leading edge and a trailing edge. Additionally, the blades may have a number of structural spars inside. Manufacturing blades for wind turbines using composite materials is labor intensive and expensive.
A blade for a large wind turbine may be from about 13 meters to about 60 meters in length. As the length of the blades increase, deflection becomes more of an issue. Deflection is a change in the shape of the blade. As a result, as the length of the blades increase, the strength of the blades also increases to reduce deflection.
These blades may be made from various materials such as fiberglass, carbon, wood, and/or other materials. In manufacturing a blade, a gel coat is typically placed on the surface of a mold for the shell. Thereafter, glass fiber layers and other parts may be placed onto the surface inside of the mold. A film may then be placed over this assembly of materials. A resin is then infused into the glass fiber materials under pressure or with vacuum assistance. Depending on the size of the blade, resin is injected into the mold from multiple locations.
Managing the flow of resin to obtain a uniform infusion of resin throughout the blade is often difficult. Inconsistencies in the resin may result in having to rework the blade or discard the blade. Having to rework the blade or discard the blade increases the cost and time needed to manufacture blades for wind turbines.
Therefore, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above as well as possibly other issues.